Regenerative repeater for inverse neutral telegraph systems



W. T. REA

Sept. 7, 194".

REGENERAI'IVE REPEAYTER FOR INVERSE NEUTRAL TELEGRAPH SYSTEMS Filed June28, 1941 2 Sheets-Sheet 1' INVENTOR W 7." REA VJ Arr-mus 2 Sheets-Sheet2 w. T. REA

Filed June 28, 1941 Sept. 7, 1943.

REGENERATIVE REPEATER FOR INVERSE NEUTRAL TELEGRAPH-SYSTEMS PatentedSept. 7, 1943 UNITED A S'IATIEZS PATENT OFFICE i "semi. a v

" REGENERATIVE REPEATER FOR INVERSE NEUTR-AL' TELEGRAPH SYSTEMS WiltonT. Rea, Bayside, N. Y., assignor to Bell Telephone.-Laboratories,Incorporated, New York, N. Y., a corporation of New York p ApplicationJune 28, 1941,:Se1ialNo. 400,248

(01. us-m,

, 10 Claims.

This invention pertains to telegraph systems of the start-stop type inwhich code signals are repeated from line section to line section andmore particularly to animproved regenerative repeater circuit forstart-stop telegraph systems.

An object of the present invention is to provide a regenerative repeatercircuitarrangedto function in inverse neutral repeater systemsfi Anotherobject of the present invention is to provide a regenerative'repeatercircuit capable of functioning in inverse neutral repeater systems whichcircuit includes facilities enabling it to function either on a halfduplex basis or on a full duplex basis at different times.

Neutral signals are closed-circuit and opencircuit signals or currentand no -current signals. Ordinarily when neutral signals are employed,the closed circuit condition or current condition is the markingcondition and the open-circuit condition .or no-current "condition isthe spacing condition. The signals herein are neutral signals in thatthey are current and no current signals but the marking signal is ano-current signal and the spacing signal is [a current signal. They areinverted from the usual neutral signals, hence the term inverse neutral.For the marking condition, inthe case of the inverse neutral repeatersdescribed herein, the conductors interconnecting repeaters arrangedforinverse neutral operation areterminated in battery of thesamepolarity and magnitude. Hence no current flows for the markingcondition. For

- the spacing condition, grcundis connected to one end of the conductorby the repeater which is sending and current flows in the conductor.

, Inverse neutral repeater circuits are well known in the art. They aredescribed in Patent 2.056.277 to F. S, Kinkead, et al., October 3, 1936,Patent 2,069,224 to G. C. Cummings, February 2. 1937, and Patent2,069,251 to F. s. Kinkead,'- Februar 2, 1937. i

The circuit herein includes a regenerative repeating mechanism wellknown in the art. It is described in detail in Patent 2,105,173 toWalter J. Zenner, et al., January 11, 1938. In the present inventionZenners regenerative repeater -echanism is disposed in a newregenerative re.- peater circuit, which circuit is designed to produceregenerated inverse neutral signals and which provides new and improvedprotection against the mutilation of abreak signal. The circuit isarranged also so that it will function on either a half duplex basis oron a full duplex hnsis at different times.

A feature of the present inventionis a regenerative repeater circuitwhich produces regenerated inverse neutral telegraph signals.

A further feature of the invention is a regenerative repeater circuitincluding a switching arrangement which permits the circuit tofunctionat one time on a half duplex basis and at anothertime on a fullduplex basis.

A further feature of the invention is anarrangement -which' providesfor'repeating break signals or other long spacing signals while thecircuit isarranged to function on a half duplex basis.

A furth'er-feature of the invention is an arrarigernentwhich preventsthe mutilation of a breaksignal as a result of the faulty of one'oftherepeating relays.

operation [A further feature of the invention is an arrangement'for'holding an idle repeater in the stopposition, when an associatedrepeater using thesameidriving motor is in use.

{of theconversion between half duplex and full duplex. operation.

Theseandfother features will become apparent from the followingdescription when read. with reference to the associated drawings, inwhich:

Fig. jl isfla circuit schematic representation of "two regenerativerepeater mechanisms driven by iasingle motor. The regenerative repeatermechanism is'described indetail in Patent 2,105,173 mentioned. above.,The figure shows also the manner in which these mechanisms areinterconnected to the repeating relay circuit of Fig. 2; and p Fig. -2is a regenerative repeater relay circuit ,arranged to cooperate withFig. 1 to regenerate inverse neutral telegraph signals.

Numbering arrangement The apparatus and wiring shownin Fig. 1 isnumbered for purposes of identification, in the one hundred series. Theapparatus and wiring merFig. 2 is numbered in the two hundred series.The conductors shown extending to the bottom of Fig. 1 connect'to'conductors extending'to the top of Fig. 2 in corresponding positions. Aconductorjsayin-Fig. 1, numbered in the one hundred seriesywhen extendedinto Fig. 2, will be numbered in the two hundred series, but the lasttwo digits of the number identifying the conductor will be the same ineach figure.

Regenerative repeater mechanism The regenerative ployed in the inverseneutral regenerative repeater circuit of this invention is, as mentionedabove, described in detail in Patent 2,105,173. Since it is well knownin the art, the principles of its operation only will be describedherein,

repeater mechanism em as a detailed knowledge of the mechanism is J notnecessary to an understanding of the present invention.

The regenerative mechanism is of the start-: I

stop type. It is designed to function in a-tele typewriter systemwherein each different char-- sented to it, the armature will beretained in its attracted or upper position. Whenever the magnet Iifl isdeenergized when armature I33 4 presented to it, the armature will notbe retained in its upper position after the projection on cam acter orfunction transmitted is identified by a" different combination of signalelements arranged in a train. length and comprises a start or spacingsignal pulse, five pulses which may be marking or spacing signal pulsesin different combinations to designate the character or the function anda stop pulse which is always a marking signal.

The regenerating mechanism retimes the pulses which have becomedistorted by their passage over the transmission circuit and restoresthem to their original lengths.

The-regenerative unit is motor driven by a synchronous or direct currentspeed controlled motor. Each motor, in a practical installation, is-

arranged to drive a number, such as four or more, regenerative units,only two of which are indicated in Fig. 1. The regeneratorsmay becoupled to the countershaft of the motorin any convenient manner. Thetwo regenerative units indicated are each shown coupled directly to themotor countershaft by means ofa friction clutch, such as I23 or I28,which is part of eachregenerative unit. When four or more regenerativeunits are driven by one motor, the driving shaft of each unit is geareddirectly to the countershaft of the motor. The driving shaft of eachunit rotates as the motor counter shaft rotates.

The driven shaft of each regenerative unit is.

prevented from rotating by means of a stop arm such as I on each unit,which engages a raised surface I 35 on the periphery of a stop cam. I31when the driven mechanism of the unit is in the stop position. In thestop position magnet IHJ is always energized. The armature I33 is raisedand the stop arm I35 is interposed in the path of raised surface I36.For the start impulse armature H0 is always deenergized. The armatureand stop arm I35 are lowered. The driven shaft makes one completerevolution before the raised surface again reengages stop arm I35 tostop rotation of the shaft.

Although the motor countershaft, as shall be shown, is rotatedcontinuously and rotates the driving shaft of each unit associated withthe motor, when any of the units is operated, the driven mechanisms ofthe regenerative units are operated individually. The arrangement hereinincludes means in the relay circuit, as shall be shown, which insuresthat. when any one of the regenerative units is to be operated and otherunits associated with the same motor are not to be operated, the unitswhich are not to be operated are conditioned, by the relay circuitassociated with the operated unit, so that their driven mechanisms areprevented from rotating. The cam assembly of the regenerative unit, saythe left-hand unit, comprises a cam I20 and follower'I I9. 'I'hefollowerI I9is integral with Each train is of uniform tions are sospaced asthrough the Winding I20, which has raised it, has moved forward, but thearmature will be withdrawn into its lower position, under the influenceof a spring, not shown.

'The cam assembly comprises also a locking cam I22, which momentarilyactuates a follower I2I to unlock the sending reed MI an instant afterthe middle of each pulse. The sending reed is pivoted on the same shaftas the armature and is flexibly connected to the right-hand bifurcatedend of the armature by a pair of centralizing springs I29 and I30. Thesending reed tends to follow the motion of the armature, due to thetensioning of spring I29 if the armature has moved upor of spring I 30if the armature has moved down. The sending reed is locked, however, bya latching arrangement on the end offollower IZI for an interval untilthe armature has-assumed its proper position, either raised or lowered,for a particular pulse. The cam I22 thereupon actuates thev follower I2Ito unlatch the sending reed for aninstant to permit the sending reed tofollow thearmature, if the final position of the armature for theparticular pulse is, different from its final position for the previouspulse. 'Ihen thefollower is instantly restored locking the reed ineither the raised or lowered p'osition,- Where it is maintained for aninterval equal to the length of a pulse. Contacts H2 or II 3 are closeddependent upon the position assumed by'thereed.

From the above itshould be apparent that each pulse is, in effect,stored for approximately one-half pulse length and is then transmittedeither as a marking pulse or as a spacing pulse depending upon whetheror not the holding magnet] It wasenergized or deenergized. The timing ofthe retransmitted pulses is determined exclusively bythe locking cam I22whose projecto operate the locking latch I2 I at intervals a unit pulselength apart. Hence the transmission times of the retransmitted signalsare correct.

Repeater circuit The repeater relay circuit per Fig. 2 employs two polarrelays 2I2 and U3, one for each di- Conditioning the circuit foroperation I r In order to condition the regenerative repeater iclrcuitherein for operation, current is supplied from the regenerative repeatercontrol circuit 2I8 to conductor 214, closing a circuit of relay 2I4 tobattery, operbet "p ntials ebmieetec t6 tire biigi'ggite a.

W 1- tHe rb'p regenerative rim '5 to "win $13 q rcuit 1431: L duplexoperation.

N p rti o ri is adequate er -5112:; 5.51 1 9 At I a were U, live r ew-W91 fiber en aw inn nus the holding-pa i's diaenlicr ench ffbn, halfdupiex' bpefat'ibh now be described in detail.

and conductor 21'! is also disconnected from the regenerative repeatercircuit at contactsv 253 of relay 2I5, as these conductors play no; partin the operation ofthe circuit when it is conditioned for half duplexoperation. "Conductor 2T8 extends through the east regenerative legmultiple circuit 2I'I to a circuit (not shown) arranged to transmitinverse neutral signals. For themarking' condition, negative battery isconnected to conductor 21-8 and a circuit may be traced through contacts259 of jack 2H, conductor 206, conductor I06, sending reed Iiii,contacts H5, conductor I01, conductor 201, contacts 260 of jack ZII,contacts 251 of relay 215, top winding of relay '2I3, resistance 231 andresistance 238 to negative battery 234. Thepctential of negative battery234 is equal to the potential of the negative battery connected to thedistant end of conductor 218. Under these conditions no current flowsthrough the top winding of ret The current flowing through the botlay2I3. tom winding of relay 2I3 is therefore effective to actuate thearmature of relay 2I3 so that it engages with its marking contact 230.With the armature of relay 2I3 in engagement with contact 230, thewinding of holding magnet Iiii of the left-hand regenerative unit isenergized. as described above. Th-efirst orstart-signal in any trainreceived from the distant circuit connected to conductor 218 will resultin ground being connected. at the distant station to conductor 218.

As a consequence, current of a magnitude sufficient so that its efiectpreponderates over the effect of current flowing through the bottomwinding of relay 2I3, will flow through the top winding of relay 2I3.Its effect opposes the effect of current through the bottom winding andthe armature of relay H3 is actuated'so as to engagewith its right-handor spacing contact 23L This opens the path through the winding of theholding magnet I I0.

When the holding magnet II 9 is energized, the transmission pathextending from the repeater circuit herein through the west regenerativerepeater leg multipleicircuit ZI G toward the west is closed. Thiscircuit'may be traced from negative battery 235 through resistance 2%,re-

sistance 241, top winding of relay 2I2, contacts 252 of relay 2I5,contacts 253 of jack 2H], conductor 203, conductor I93, marking contactsI I3 of the left-hand regenerative unit, sending reed MI, conductor I04,conductor 264, contacts 262 of jack 2I0, conductor 219, and through thewest regenerative repeater leg multiple circuit 2I6 toward the west,where it is terminated in negative battery of the same potential as the'potential of battery 235. This results in a marking signal beingreceived at the distant station. When contacts IIZ of the left-handregenerative unit are closed, in response to a spacing signal from theeast, a circuit is established from ground through contacts IIZ, sendingreed. I4I, conductor IIM, conductor 204, contacts 262 of jack ZIIl, andconductor 279 toward the west, resulting in a, spacing signal being sentto the distant station. At

signals received from the east.

signal.

hand regenerator unit. As the'left-hand regenerator' unit is operated,the circuit to the West is either connected to negative battery 235,when contacts I I3 are closed, or is connectedto ground when contactsII2 are closed. Thus inverse neutral signals are transmitted, throughtherepeater herein from the east towards the west.

In transmitting from west to east, the signals are received by relay 2 I2, which in turn controls the holding magnet III of the right-handregenerative unit. When contacts I I5 of the unit are closed, negativebattery 234 isconnected to the transmission conductor extending towardthe east. When contacts I I I are closed ground is connected to thetransmission conductor extending to the east.

Transmitting a. break signal The circuit herein is arranged in suchmanner that, while it is conditioned for half duplex operation, a breaksignal may be transmitted from the end of. the circuit which ismomentarily receiving, in order to stop transmission from the oppositeend. The manner in which this is performed is as follows? a It will beassumed that the western circuit is transmitting toward the easterncircuit and that the eastern circuit breaks. In'order to do this a longspacing signal is transmitted from the east. Ground is thereuponconnected to conductor 218. If holding magnet III is energized andcontacts I I5 are closed as a result of a marking signal transmittedfrom the west, when the distant end of conductor 218 is grounded,contacts 23i of relay 2I3 will be closed immediately.

If not,' contacts 23! will be closed when contacts I I5 are closed inresponse to the next marking Under this condition contacts 233 ofrelayZIZ which receives signals from the'west are short-circuited, tomaintain holding magnet III energized, thus maintaining contacts II5closed,

v to prevent further transmission from the west toward the east. Theshort-circuiting path around contacts 233 may be traced from theright-hand or marking contact of relay 2I2, through conductor 280,contacts 254 of relay 2I5 and contacts 23I of relay. 2I3 to the junctionof the connection with the armature of relay 2I2 and the path whichextends through contacts 224 of remitted toward the circuit to the westas a break signal. a

The circuit is arranged correspondingly so that a breaksignal may betransmitted from the west toward the'east. This operation will not bedescribed in detail as it should be obvious from ascents ,5

referencetoythed e rinesrancithe erceoinefdea Wa e ,iqrn oi: the oerating tin es jqiii scription;

nni he eins ma n t nee-condenser I I Fullduplcx o eration I The-@651 Inord r to transmit n hothrdiieet h taneously e op a o a ithei eh o the eenerative repea e con rol chew. 7. located, wi l open conductor. 3 5 reeasing e 215. In vlfl ll duplex operati conductors and 218 extendingtoward the east are both re.-

quiredand the corresponding conductors 211 and 21%! extending toward thewest are both required.

It is pointed out that by full duplex operation 20 1941 of inverseneutral circuits is meant, not simul- What i lai ed, is; taneouslytwo-way operation over a single con- 1 In telegraph y tem a regenerativet s such operation s not possible in i peater circuit, a polar receivingrelay in said cirverse neutral circuits. In order to transmit intbiasing winding, transmission line windtwo directions simultaneously,an independent ing, an m ture and a pair of opposed marking circuit in'each direction is required. It is to be a d spacing t t ,11 on i l 1 1understood therefore that, the term, full 0111- cult means in saidrepeater circuit for applying r e s applied to inverse neutral circuits,means a constant and continuous force through said sim an u w ytransmission over two biasing winding on said armature to direct saiddependent transmission paths and not simularmature toward said markincontact, means tan ous tw -way transmission vera single path.for-connecting batteries or equal magnitudes and The manner in whichsignals are transmitted of the same potentials to opposite ends of saidfrom the east to the west will first be described. li 'winding at afirst time, means for connecting For the rk condition negative batteryis ground to the distant end of said line winding to connected toconductor 216 and a circuit may be a tuate said armature to engage withsaid spactraced through contacts 25% of relay 01 ing contact at a secondtime, a motor-driven cam winding of relay 2i3, resistance 23? andresistmechanism in said circuit, means also in said cirahee 23B tonegative battery e b e e cuitnresponsive to said relay for controllingsaid are of equal potential. The armature of relay mechanism, and meansresponsive to the opera- 253 is actuated under the influence of currentti n f id m h i for regenerating and thlmlgh t bottom Winding of relay2L3 so as i transmitting improved inverse neutral signals as to closecontacts 233. This energ es ho ding impaired signals are received bysaid relay. magnet Ht closing contacts H3 and results in 2 In atelegraph system in combination, an the transmission of a marking signaltoward the lectromechanical telegraph signal receiving and west overconductor 219. The circuit for this retransmitting mechanism, means insaid mechy be traced from e e battery 234 threugh anism for storing atelegraph signal for an interlesistanees and Contact/$255 0f relay 40Val substantially equal to the length of one-half c n a ts 6 o j kConductor d of said signal, circuit means connected to said tor H13,contacts H3,sending reed Ml, conductor mechanism for receiving inverseneutral t 1 o du Contacts 252 Of jack 2!!! d graph signals and circuitmeans also connected to o ucto 2W to the distant Western said mechanismfor retransmitting regenerated tion, where the circuit is terminated innegative inver e neutral telegraph signals.

e y 0f the Same potential as battery 23%. 3. A telegraph system inaccordance with claim Ground is connected to conductor 216 for the 2including remot control switching means for Spacing Condition Thearmature of relay 2E3 arranging said system to transmit in either of isc ed s as to engage w h a s 3 two directions alternately during a firsteriod The windin of ho din a ne H 0 ciee -v and including also remotecontrol switching s d and ts H2 ar s This nds means for arranging saidsystem to transmit in conductor 219 and a spacing signal is transmittede h of t o directions simultaneously during a to the distant westernstation. e ond period,

In transmitting from the west toward the east 4, A system in accordancewith claim 2 includfor the marking Condition negative ry is ing remotecontrol means for energizing said connected to conductor 21! and thecircuit may hani m, be traced through contacts 253 of relay 2l5, top 5,A system in accordance with claim 2 includwinding of relay 212,resistance 241 and 'resisting r mote control means for energizing bothof ance M6 to negative battery 235. The armature said circuit means. frel y 212 en contacts 3 for this eondiso '6. A system in accordance withclaim 2 includtiOh- Holding magnet H! is energizede ing remote controlmeans for energizing said spacing condition ground is connected toconmechanism and remote control means for enerductor 211. The armatureof relay H2 is actugizing both of said circuit means. ated so as toengage its contacts 232. This de- 7 A system in accordance t claim 2energizes holding magnet IH. Contacts H5 and c5 eluding remote controlswitching means for con- IM e ed and Op e alternately to sditioning saidsystem for alternate one-way or mit marking and Spacing a s toward theeast simultaneous two-way transmission and includover conductor 218. ingalso other remote control means for energizing said mechanism.Mzsveuaneoug apparatus 8. In a telegraph system, a regenerative re- C ese 39, 5 a d 8 e Wa peater mechanism of the start-stop type, a relayshaping condensers. The resistance-condenser circuit cooperating withsaid mechanism, a first networks 264, 265, 266 and 261 connected acrossand a, second polar telegraph signal receiving rethe contacts of thepolar relays serve, not only l i s id i it a tu d a pair of G to protectthe contacts, but also to shape the posed contacts oneach of saidrelays, means in said circuit for permitting a distant connected stationwhich is receiving to break a distant connected station which issending, and means for short-circuiting the armature and one of saidcontacts on the relay which has been receiving 5 to insure apositivebreak. a y

9. In a telegraph system, a regenerative re-' peater, a telegraph lineconnected to said repeater, a telegraph signal receiving relay in saidrepeater, an armature and a contact on said relay, and means forshort-'circuiting said armature and 10 through said line.

WILTON T. REA.

